1. Field of the Invention
With the increasing scarcity of liquid fuels, such as oil, there have been increased efforts to find substitute sources of thermal energy. One of the promising sources is to use a combination of small particulate coal dispersed in heavy oils. However, such dispersions inherently have a number of problems. The coal is partially soluble in the oil, so that the coal particles swell and can cause gellation of the slurry. Secondly, materials extracted from the coal by the oil can greatly enhance the viscosity of the slurry, so as to make the slurry only difficulty flowable. Finally, it is necessary to provide a stable dispersion or a dispersion which can be reconstituted with mild agitation. It has been found that coal has a tendency to settle with time in oil-coal slurries.
2. Description of the Prior Art
See U.S. Pat. No. 3,661,815 for a description of a modified starch and U.S. Pat. No. 3,907,134, and the patents cited therein for a description of coal-fuel slurries.